Android updates are getting notoriously slow to rollout, and there often isn't a set release date when it occurs.  Generally, there is some warning from the company, such as Sony, and their users are anxiously awaiting the Android update to Marshmallow (also known as Android M or 6.0) to the Xperia Z2, Z3, Z3+, and Z4 (not to mention any word on the new Z5).  Some of these phones have not received the Android 5.1.1 rollout, so when will that Marshmallow 6.0 get here?

According to Android Pit, Sony has remained silent on their update schedule, but the Xperia Z4, Xperia Z3, Xperia Z3 +, as well as the Xperia tablet will "certainly receive the update to Android Marshmallow".  Apparently, there was an Android M preview made available for select Xperia devices, the update will probably be rolling out soon. 

The big question is when.  According to Neurogadget, Sony just had a rollout of Android 5.1.1.  This was long-delayed thanks to Stagefright.  Stagefright being the Android media playback service that can unpack and play multimedia messages, and there is a vulnerability that could allow hackers to get media privileges of your device when processing an MMS, without any need of end-user action.   Sony has received patches from Google in order to address the issue of Stagefright and making them available through carrier networks within the software maintenance updates. 

Unfortunately, that rollout appeared to have taken place in certain countries like Spain and Austria, but it might be available in the United States.  Users of the Z3, Z3+, and Z2 are encouraged to check their Settings on their Android Xperia device to see if this update has been made available.  If not, then it is quite possible that some Sony's older flagship phones could potentially skip the Lollipop 5.1.1 update and just skip straight to Marshmallow 6.0. 

This also leads to the question about the newly announced Xperia Z5, not to mention the Z5 Compact and the Z5 Premium.  Is it possible that they could be getting some Marshmallow 6.0 right out of the box?  Well, the Xperia Z5 and the Z5 Compact are slated to be launched globally starting October 2015, with the Xpereia Z5 Premium starting on November 2015. It is possible that Marshmallow could be available to them at the time, which would be welcome as new users will pick up these phones just in time for the holiday season. 

According to Neurogadget, Sony did post on its website the models that will be at least attempting to run that the operating system. 

• Xperia Z3 Plus
• Xperia Z4 Tablet / Wi-Fi
• Xperia Z3
• Xperia Z3 Compact
• Xperia Z3 Tablet Compact
• Xperia Z2, Xperia Z2 Tablet
• Xperia Z1
• Xperia Z1 Compact
• Xperia Z Ultra
• Xperia Z
• Xperia ZL
• Xperia Tablet Z.

Unfortunately, no official release date for Marshmallow has been announced for the Sony Xperia series.